Disclosed herein are high refractive index monomers and curable coating compositions prepared from such monomers. The compositions and monomers are suitable for optical articles and particularly for light management films. Also disclosed herein is a method of preparing high refractive index monomers.
In backlight computer displays or other display systems, optical films are commonly used to direct light. For example, in backlight displays, light management films use prismatic structures (often referred to as microstructure) to direct light along a viewing axis (i.e., an axis substantially normal to the display). Directing the light enhances the brightness of the display viewed by a user and allows the system to consume less power in creating a desired level of on-axis illumination. Films for turning or directing light can also be used in a wide range of other optical designs, such as for projection displays, traffic signals, and illuminated signs.
Compositions used to form light management films to direct light desirably have the ability to replicate the microstructure needed to provide the light directing capability upon cure. It is furthermore desirable for the glass transition temperature (Tg) of the cured composition to be high enough for shape retention during storage and use. It is also desirable for light management films made from the cured composition to exhibit high brightness. Finally, the composition used to make light management films advantageously provides a cured composition having a high refractive index. While a variety of materials are presently available for use in light management films, there remains a continuing need for still further improvement in the materials used to make them, particularly materials that upon curing possess the combined attributes desired to satisfy the increasingly exacting requirements for light management film applications.